God damn it. The Akatsuki likely lose every scenario.
>Absorbing the chakra of the FTG duo, for Kisame, gives them either a foothold to teleport over to them or teleport Samehada away. As it was, Bee's chakra was still detectable inside Kisame's jutsu after fusing with Samehada.
>Gai hard counters Kisame to the point of canon. Kakashi may or may not beat Itachi, but Itachi cannot beat both Gai and Kakashi. Likewise, if they switch it up, Kisame will likely be sniped by Kamui when kakashi is too pressured by Kisame's beastly nature.
As for the others, I'm not sure. I know people have debated for Gai vs both, but I ain't too knowledgeable on Gai's reactions and precisely what his striking speed is to defeat either of them in CQC.